Clutches of the type used in torque converters are actuated in an engaging direction in order to connect the drive input of the torque converter to its drive output, whereby a direct driving connection from the drive input to the drive output is formed, which results in improved efficiency. Such clutches are often actuated in the engaging direction if the turbine torque and the pump torque have almost the same value with the clutch engaged or disengaged. This shifting point is determined from the rotation speed difference between the pump wheel and the turbine wheel of the hydrodynamic torque converter.
Working machines, such as agricultural vehicles, or building machinery, such as wheel loaders, additionally comprise an auxiliary power take-off which is in active connection with the drive input of the torque converter.
DE 33 47 256 C2 discloses a control device for the bridging clutch of a hydrodynamic torque converter in which an auxiliary power take-off, in the form of a shaft, is driven by the drive engine and the bridging clutch is actuated in the disengaging direction if it is detected that the speed has fallen below the lowest power take-off shaft rotation speed.